Instrument-free fabrication of microfluidic paper-based analytical devices through 3D pen drawing

This paper describes for the first time the use of a 3D pen to fabricate paper-based analytical devices. 3D pens are usually commercialized as toy for children and a kit containing four units and a handheld flashlight can be found at cost of US$ 10 -15. The protocol involves the 3D pen drawing of the desirable layout on paper using an acrylic resin followed by a curing stage through a handheld flashlight. The barriers created with 3D pen revealed good chemical resistance when exposed to acid and alkaline solutions, surfactants and organic solvents, except ethanol. The proposed approach enabled the creation of zones with 2 mm diameter and channels with 3 mm wide. The analytical feasibility of the devices created with 3D pen was investigated through colorimetric measurements of clinically and environmentally relevant analyzes using a free application for image capture and analysis. Considering the instrumental simplicity and the satisfactory analytical performance, we believe the reported approach exhibits potentiality to be implemented in laboratories or research centers with limited resources, opening possibilities to create the desirable devices for the point-of-need applications using only a pen and a flashlight.